'[Sheldon reveals that Leonard betrayed both Raj and Howard's trust by sleeping with Raj's sister, Priya]
Raj: [getting up to leave] I don't believe it. This is a terrible betrayal of my trust.
Leonard: No, no - would it help if I told you that I offered her my heart and that she kind of stomped on it?
Raj: ... How hard did she stomp?
Leonard: Very hard!
Raj: Okay, I'm good. [Sits back down]
Howard: Raj, I just want to say I'd never betray your trust. Unlike Leonard, I respect you.
Leonard: Really? Was it out of respect that you didn't tell Raj about the time you dropped his iPhone in a urinal?
Raj: [horrified] DUDE, I PUT THAT THING ON MY FACE!
Sheldon: I think a more amusing violation of Raj's trust is when Howard convinced him that foreigners give presents to Americans on Thanksgiving.
Howard: Hey, I didn't see you giving back your Snoopy Snow-cone maker!
Raj: That was all a lie!? This year's gifts are already wrapped!
Howard: And as long as we're talking about betraying our friends, how about the month Sheldon spent grinding up insects and mixing them into Leonard's food?
[Leonard looks horrified]
Sheldon: Well, excuse me! That was not a betrayal. That was an experiment to determine at what concentration food starts tasting "mothy."
Leonard: YOU PUT MOTHS IN MY FOOD!?!?!?
Sheldon: For science.
'Raj": I can't believe you kissed my sister with moth mouth!
Leonard: Well, I can't believe you used Sheldon's toothbrush!
Sheldon: YOU USED MY TOOTHBRUSH!?!?!?!?!??!!?!??!
Raj: Not the brush part, just the little rubber thing to pick food from my teeth and massage my gums.
[Sheldon starts blinking furiously]

Amy: I find the notion of romantic love to be an unnecessary cultural construct that has no value to human relationships.
Sheldon: Amy Farrah Fowler, that's the most pragmatic thing anyone has ever said to me.
Amy: I trust this clarification allows us to return to boy-slash-friend-slash-girl-slash-friend status?
Sheldon: Of course. Would you like to join me for Chinese food?
Amy: Sheldon, please, you're suffocating me.

Amy: Penny's friend, Zack, stopped by and said "hello" and I said "hoo!"
Sheldon: Hoo?
Amy: Zack.
Sheldon: Then why did you ask?
Amy: Ask what?
Sheldon: Who?
Amy: Zack.
Sheldon: Alright, let's start over. What did you say when Zack walked in?
Amy: Hoo!
Sheldon: Zack.
Amy: Why do you keep saying 'Zack'?
Sheldon: Because you keep saying 'Who'.
Amy: I'm not saying 'hoo' now. I said 'hoo' last night.
Sheldon: And the answer was Zack, correct?
Amy: There was no question; I simply said "Hoo!"
Sheldon: [short pause] All right. I think I have enough to go on.

Amy: So anyway to make a long story short, turns out I have an unusually firm cervix.
Penny: You know Amy, when we say girl talk that just doesn't have to be about our lady parts.
Amy: [That's a] Shame, cause I have a real zinger about my tilted uterus.
Penny: So what do you girls wanna do tonight? Should we go to the club or to the movies?
Bernadette: Or we could just stay here?
Amy: Yes, and continue to bond. I have a feeling that after tonight, one of you will become my best friend forever, or BFF if you prefer - which I don't.

Amy: Well, the Internet suggests that another popular slumber party activity is experimentation with lesbianism.
Bernadette: Where exactly on the Internet have you been looking?

Bernadette: So we just sit and stare at a screen and wait for something to happen?
Howard: I did it with you when we rented The Notebook.

Howard: Hey, how'd it go?
Bernadette: You're a putz! You know what that means?
Howard: Yeah, do you?
Bernadette: Your mother just taught it to me. She thinks she got food poisoning from that deli and she wanted to make sure I was okay.
Howard: And are you?
Bernadette: No, because I'm engaged to a putz. You let me believe I was the reason she had a heart attack.
Howard: Well, based on the available evidence...
Bernadette: Shut up! She said I'm a wonderful girl and that you're lucky to have me.
Howard: [as Bernadette walks away] Where are you going?
Bernadette: [like Mrs. Wolowitz] To the toilet! Is that okay with you?!
Howard: [to Leonard and Raj after she leaves] Is it just me or does she sound sexy when she's angry?

Howard: Hey, Raj, did you ever tell your sister about the time Sheldon got punched by Bill Gates?
Priya: Oh God, you're kidding!
Raj: [laughing] No. Gates gave a speech at the university. Sheldon went up to him afterwards and said "Maybe if you weren't so distracted by sick children in Africa you could have put a little more thought into Windows Vista."
Leonard: [laughing at the memory] Bam! Right in the nose! Made me proud to own a PC.

Howard: Hey, what's up?
Mrs. Wolowitz: Is that my future daughter-in-law, the doctor?
Howard: No mom, it's Raj!
Mrs. Wolowitz: He's a doctor too, right?
Howard: Yes.
Mrs. Wolowitz: Like Leonard and that skinny weirdo?
Howard: Sheldon: Yes, everyone is a doctor but me.
Mrs. Wolowitz: And whose fault is that?
Season 5

Howard: Who'd want to become "RatMan"?
Raj: Who wouldn't?!?! You could zip through a maze in nothing flat, uh, squeeze through really small holes, and shut down restaurants in a single bound! And the best part of it is, if I were RatMan, you could be my sidekick; "MouseBoy".
Howard: MouseBoy?
Raj: You don't like MouseBoy? How about "Kid Vermin"?
Howard: First of all, if we were going to have superpowers I would not be the sidekick; YOU'D be the sidekick.
Raj: RatMan is nobody's sidekick!
Howard: Leonard, settle this. Of the two of us, who's the obvious sidekick?
Raj: Yeah Leonard, who?
[long pause]
Leonard: Twelve years after high school and I'm still at the nerd table.

Leonard: Morning, Sheldon.
Sheldon: Oh, good. You're up. I've written a new and improved roommate agreement that benefits me greatly. I'd like you to sign it.
Leonard: Why would I want to do that?
Sheldon: Excellent question. Do you remember what happened to the alien, played by talented character actor Frank Gorshin, in the Star Trek episode "Let That Be Your Last Battlefield"?
Leonard: Uh, Captain Kirk activated the self-destruct sequence and threatened to blow up the Enterprise and kill them both unless he gave in?
Sheldon: Affirmative. [Turns to laptop] Computer, this is Dr. Sheldon Cooper. [laptop beeps in response] Activate self-destruct sequence. Code 1-1-A-2-B.
Voice from laptop: Self-destruct sequence activated.
[Sheldon turns the laptop toward Leonard and Priya, showing a timer counting down from one minute]
Leonard: What are you gonna do, Sheldon, blow up the apartment?
Sheldon: That was my first thought, but all my cool stuff is here.
Priya: So what happens when it counts down?
Sheldon: Unless Leonard signs the new agreement in the next��[checks timer] 41 seconds, this computer will send an e-mail to your parents in India saying that you're in a secret relationship with the whiter-than-Marshmallow-Fluff Leonard Hofstadter.
Priya: [worried] Oh, my God.
Leonard: What's the big deal?
Priya: Trust me, it's a big deal.
Leonard: They're gonna find out about me eventually, right?
Priya: Yeah, of course, just not today.
Sheldon: 20 seconds.
Leonard: Are you ashamed of me?
Priya: Of course not.
Leonard: Then why can't we just tell your parents?
Priya: Please don't push this.
Sheldon: He does that all the time, doesn't he? 15.
Priya: Okay, fine, Sheldon, you win. Turn it off.
Leonard: No, he's bluffing.
Sheldon: I never bluff. 10.
Leonard: It's blackmail!
Sheldon: 9.
Priya: We give up.
Sheldon: 8.
Leonard: [unhooking the laptop] This is ridiculous.
Sheldon: It's a laptop with a full charge. [to Priya] Honestly, what do you see in him?
Priya: Okay, give him what he wants or we're done.
Sheldon: 3.
Leonard: Really?
Sheldon: 2.
Leonard: Okay, I'll sign it!
[Sheldon hits a key and places a pen on the agreement]
Voice from laptop: Self-destruct sequence aborted.
Sheldon: [to Priya as he stands up and leaves] You may have gone to Cambridge, but I'm an honorary graduate of Starfleet Academy.

Leonard: That's great news about you and Bernadette [getting back together]!
Howard: Yeah, I think I'm going to take her to miniature golf.
Leonard: Oh, well, I guess for you guys, that's like regular golf.
Howard: Short jokes, really? You're like a quarter of an inch taller than me!
Leonard: Yeah, and don't you forget it!

Leonard: You'll never guess what just happened!
Sheldon: You went out in the hallway, stumbled into an interdimensional portal which brought you 5,000 years into the future where you took advantage of the advanced technology to build a time machine, and now you're back to bring us all with you to the year 7010 where we are transported to work at the thinkatorium by telepathically controlled flying dolphins?
Leonard: No.
Sheldon: [Genuinely dissappointed] Aw.
Leonard: Penny kissed me.
Sheldon: Well, who would ever guess that?

Mrs. Wolowitz: [as Howard is unlocking the front door] Who's there!? Are you a sex criminal!?
Howard: Sex criminals don't have keys, Ma! [goes inside]
Mrs. Wolowitz: Where were you so late!?
Howard: I was out with Bernadette!
Mrs. Wolowitz: I know what that means! I watch Dr. Phil! [short pause] I hope to God you used a condom!
Howard: I'm not having this conversation with you, Ma!
Mrs. Wolowitz: God forbid you get one of those new fancy sex diseases!
Howard: Nobody has a disease!
Mrs. Wolowitz: I hope not! I share a toilet with you! Is that what you want!? To give your mother herbies!?
Howard: That's it! I don't have to take this! [comes back outside, yelling at the front door] And good luck with your eyebrows in the morning!
[He starts to leave, then goes back to the door and unlocks it again]
Mrs. Wolowitz: Who's there!? Are you a sex criminal!?
Howard: [going back inside] Still leaving; I just forgot my Claritin!

Penny: [about going with the others to a science conference including a spa treatment] Boy, this is great. I haven't had a vacation in ages!
Sheldon: In order to take a vacation, one first has to work.
Penny: You know, for a smart guy, you really seem to have a hard time grasping the concept "Don't piss off the people who handle the things you eat". [leaves]
Amy: That does seem to be a valid principle.
Sheldon: [waves her off] I trust Penny will adhere to the official California Restaurant Worker's Solemn Oath of Ethics and Cleanliness.
Amy: I don't believe there's any such thing.
Sheldon: [to Leonard] You lied to me?